The most common form of restraint for infants under 6 months of age, is a child seat that locates within a motor vehicle so that the infant is rearward facing with respect to the vehicle. The restraint comprises a base that is secured with respect to the vehicle seat and an infant seat that locates within the base. The vehicle seat belts may be used to secure the base to the vehicle seat. The infant seat has restraining means such as a harness within the seat to hold an infant with respect to the seat.
Examples of such infant restraints are shown in Australian Patent No. 548416 and U.S. Pat. No. 4,943,113. Such infants seats as shown in the two patents use a latching mechanism to hold the infant seat with respect to the base. In both instances, the latching mechanism automatically engages upon an infant seat being placed with respect to the base and, has a manual release mechanism to allow the seat to be released from the base. This latching mechanism is relied upon to provide a sufficient holding force to hold the infant seat with respect to the base under collision loads.
An important requirement is to ensure that, during collision, the head end of the infant seat does not rotate downwardly to an extent that is greater than the prescribed limits. Such limits are generally prescribed by standards such as the United States Federal Motor Vehicle Standard FMVSS213 and other equivalent international standards.
Factors that contribute to downward rotation of the head end of the infant seat are compressibility of the vehicle seat and movement of the infant seat with respect to the base.
It is common for the base to be restrained with respect to the vehicle seat by the vehicle seat belts. The seat belts engage the base at a point that is close to the backrest of the vehicle seat. During collision, there is generally both forward force resolving from the rapid deceleration of the vehicle together with a downwards force causing rotation of the infant seat and base about the seat belt restraint so as to compress the vehicle seat.
In addition, there will be movement between the infant seat and the base. The base and infant seat are generally injection molded plastic components and so there will be some flexibility, particularly under high loads. Accordingly, the infant seat can move forward with respect to the base when impact forces are applied to the infant seat.
The combination of deflection resulting from deformation of the plastic components together with compression of the vehicle seat will often lead to an extent of rotation that is unacceptable.
Accordingly, it is an object of this invention to reduce the extent of rotation of the infant seat.